JPH0478696B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] This invention relates to the production of high-strength aluminum alloy members for producing high-strength aluminum alloy members of a predetermined shape by hot forming aluminum alloy solidified bodies prepared by a rapid solidification method. It is about the method. [Prior art and its problems] In recent years, new types of alloys produced by the rapid solidification method are expected to be applied in various fields. The rapid solidification method enables the formation of uniform solid solutions of alloying elements, the formation of supersaturated solid solutions, and the fine dispersion of intermetallic compounds, which were previously considered difficult. In some cases, alloys can be obtained, and the properties of alloys can be greatly improved. However, the rapid solidification method generally involves rapidly cooling a small amount of a molten alloy by contacting it with a large amount of a gaseous or liquid cooling medium, or by causing it to flow down onto a rapidly moving cooled solid surface. Therefore, the solidified metal obtained by this method must have a fine shape such as powder, flake, or thin ribbon. Therefore, the finely shaped solidified metal thus obtained needs to be processed into a member of a predetermined size, except for special purposes in which it is used in its finely shaped form. For example, in order to manufacture aluminum alloy members such as plates, bars, and shapes for structural materials from a microsolidified aluminum alloy produced by the rapid solidification method, it is generally necessary to A forming process is required in which a preform is prepared by collecting and compressing an aluminum alloy, and then the preform is subjected to a forming process by stretching such as rolling, extrusion, and forging. The above-mentioned forming process is preferably carried out hot from the viewpoints of firm adhesion of micro-shaped solidified metals to each other through thermal activation and reduction of power during forming process. However, when hot forming is performed, the favorable nonequilibrium structure formed by rapid solidification returns to an equilibrium state through thermal activation, resulting in most of the properties obtained by rapid solidification. There is a problem that the data disappears. This is because the supersaturated solid solution formed by rapid solidification thermally decomposes into a low-concentration solid solution and an intermetallic compound, and the microcrystalline structure becomes coarser, causing the rapidly solidified structure to change in quality. It's for a reason. In the case of aluminum alloys manufactured by conventional melting and casting methods, the solid solution amount of transition metal elements such as Fe is approximately 0.1wt.% in an equilibrium state, but in the case of rapidly solidified aluminum alloys, it is approximately 10wt.%. %. Therefore, it is relatively easy to obtain rapidly solidified aluminum alloy powder or flakes with a Witzkars hardness of 200 or more, and if a thin ribbon-shaped rapidly solidified aluminum alloy is subjected to a tensile test as it is, it will have a hardness of 50 Kgf/mm ² The above tensile strength is shown. However, when such a rapidly solidified aluminum alloy in the form of a microsolid is subjected to forming processing including hot stretching to form a member into a predetermined shape, the Witzkars hardness of the member is approximately 100.
Then, the tensile strength decreases to about 30 Kgf/mm ² and the high hardness and high strength properties obtained by rapid solidification are lost. In order to prevent such a decrease in hardness and strength, if the forming process is performed cold, the strong surface oxide film unique to aluminum alloys will prevent the microsolids from adhering to each other, so it is necessary to use high-quality molded parts. can't get it. Therefore, the above molding process was performed for 200 to 300
If carried out at a so-called warm temperature of °C, there will be relatively little thermal decomposition of the rapidly solidified structure and it will be possible to bond between microsolids, but on the other hand, since a large force is required for forming, the resultant formed part will be It is not practical because it is limited in size and shape and requires special equipment for molding. [Object of the Invention] Therefore, the object of the present invention is to provide a method for producing high-density aluminum alloy members by the rapid solidification method.
To manufacture high-strength aluminum alloy members that do not lose strength even when subjected to hot drawing processing, maintain the excellent properties obtained by rapid solidification, and have appropriate ductility. The goal is to provide a method for [Summary of the Invention] The present inventors have discovered that when manufacturing high-strength aluminum alloy members using the rapid solidification method, there is no decrease in strength even when hot drawing is performed, and the rapid solidification process is effective. Intensive research has been carried out to develop a method that maintains the excellent properties obtained. As a result, the hardness and strength of aluminum alloys containing a certain amount of manganese and molybdenum are increased by rapid solidification, and the properties obtained by this rapid solidification are In addition, if part of the manganese in the above aluminum alloy is replaced with at least one of iron, nickel, and cobalt, the strength after hot working will further increase and the ductility will also improve. I found out that this happens. This invention was made based on the above findings, and includes Mo: 4.0 to 12 wt.%, Mo: 0.2 to 4.0 wt.%, and, if necessary, Fe: 0.1 to 4.0 wt.%, Ni: Aluminum with a composition consisting of at least one element selected from the group consisting of 0.1 to 4.0 wt.%, Co: 0.1 to 4.0 wt.%, the total amount of which is 4.0 wt.% or less, and the remainder: aluminum and inevitable impurities. An alloy is melted, and then the aluminum alloy is melted at 10 ³ °C/sec.
Rapid solidification is performed at the above cooling rate to prepare a powdery or flaky solidified body, and the solidified body thus obtained is directly used as
or preformed and at least once at 500℃
The present invention is characterized in that it is hot-formed at a temperature below and thus produces an aluminum alloy member having a predetermined shape and high strength. [Structure of the Invention] In the present invention, the reason why the chemical composition range of the aluminum alloy is limited as described above will be described below. (1) Manganese (Mn) Manganese is a transition metal element along with iron, and when it is precipitated as a supersaturated solid solution or finely dispersed in aluminum using the rapid solidification method, it has the effect of significantly improving strength. In addition, because thermal diffusion is slow, Al-Mn alloys have excellent thermal stability and are approximately
Shows high strength at high temperatures up to 300℃. Al−
Comparing Mn alloys with Al-Fe alloys, Al-Mn alloys tend to form a supersaturated solid solution even at a lower cooling rate than Al-Fe alloys, and their lower melting points make melting easier, resulting in higher elastic modulus. In addition, it has better properties than Al-Fe alloys, such as excellent corrosion resistance. If the manganese content is less than 4.0wt.%, the desired effects described above cannot be obtained, while even if the manganese content exceeds 12wt.%, no particular improvement in the above-mentioned actions occurs, and vice versa. However, the problem arises that the amount of intermetallic compounds produced is too large, resulting in a decrease in ductility. Therefore, the manganese content should be limited within the range of 4.0 to 12 wt.%. (2) Molybdenum (Mo) Although Al-Mn alloy has the excellent properties mentioned above, it has the problem that the above properties are significantly reduced due to thermal decomposition during hot forming after rapid solidification. There is. Molybdenum solves the above-mentioned problems of Al-Mn alloys, and by adding molybdenum, the thermal decomposition of the rapidly solidified structure that occurs during rapid solidification is slowed down, and the process of rapid solidification and hot forming is improved. The combination has the effect of significantly improving the strength of the aluminum alloy member. If the content of molybdenum is less than 0.2wt.%, the desired effects described above cannot be obtained, while if the content of molybdenum exceeds 4.0wt.%, the amount of intermetallic compounds formed is too large, resulting in ductility. A problem arises in which the value decreases. Therefore, the content of molybdenum is from 0.2 to
It should be within the range of 4.0wt.%. (3) Iron (Fe), nickel (Ni) and cobalt (Co) Iron, nickel and cobalt are Al−Mn−
It has the effect of improving the strength of Mo alloy,
The degree of strength improvement is slightly greater than that of the same amount of manganese. Additionally, iron, nickel, and cobalt have the effect of increasing the ductility of aluminum alloy members through a combination of rapid solidification and hot forming. Therefore, replacing a portion of manganese with at least one of iron, nickel, and cobalt in an Al-Mn-Mo alloy can increase tensile elongation in addition to slightly improving strength. If the content of at least one of iron, nickel, and cobalt is less than 0.1 wt.%, the desired effect cannot be obtained in the above-mentioned action; If it exceeds 4.0 wt.%, the amount of intermetallic compounds produced will be too large, resulting in a problem that the ductility will be reduced. Therefore, the content of at least one of iron, nickel and cobalt should be in the range of 0.1 to 4.0 wt.%, and their total content should be no more than 4.0 wt.%. . The Al-Mn-Mo alloy with the above-mentioned composition range is
High strength properties are exhibited by rapid solidification from a molten state, but the cooling rate should be 10 ³ °C/sec or higher. That is, by rapidly cooling a melted aluminum alloy having the above-mentioned composition at a cooling rate of 10 ³ °C/sec or more and hot forming a powder or flake solidified body, it is possible to achieve the conventional high strength. A high-strength aluminum alloy member can be obtained that has room temperature strength comparable to that of aluminum alloys, and heat resistance and rigidity that exceed conventional alloys. If the cooling rate is less than 10 ³ °C/sec, the alloying elements will not form a sufficient solid solution and coarse intermetallic compounds will precipitate, making it impossible to obtain an alloy member with excellent strength and ductility through hot forming. . Note that even if powder or flakes that have been rapidly solidified at a cooling rate of 10 ⁵ °C/sec or more by means such as the rotating roll method are used, the strength of the hot-formed alloy member will hardly be improved; It should be noted that the rapid solidification method is not economical and increases manufacturing costs. The cooling rate with the normal gas atomization method or water atomization method is 10 ² to ^{10 4} °C/sec, and the cooling rate with the improved gas atomization method or rotating roll method is 10 ⁴ to ^{10 6} °C/sec. It is. Therefore,
The rapid solidification can be carried out by the above-mentioned known method. A powdery or flaky solidified body obtained by rapid solidification under the above conditions, or a thin flaky microsolidified body obtained by cutting a thin ribbon, or a finely ground powder if necessary, As it is or after preforming, it is necessary to perform hot molding at least once to form it into a desired shape, such as a plate, bar, or profile.
Such hot forming processing can be performed by known means such as hot pressing, hot isostatic pressing (HIP), hot rolling, hot extrusion, and hot forging. The processing temperature during hot forming should be below 500°C. In other words, when the processing temperature exceeds 500℃,
As a result of rapid thermal decomposition of the rapidly solidified structure, the desired strength cannot be obtained. Preferred temperature range is 350-480℃
If the forming process is carried out in this temperature range, thermal decomposition of the rapidly solidified structure is almost suppressed, and the formed alloy member exhibits practically significant strength characteristics.
Moreover, it does not exceed the capabilities of molding equipment that is generally used industrially. [Embodiments of the invention] Example 1 Three types of alloys A, B, and
C was dissolved. Alloy A is an Al-Mn alloy outside the scope of this invention that does not contain Mo, and alloys B and C are Al-Mn-Mo alloys within the scope of this invention that contain a certain amount of Mo.

[Table] The above alloys A, B, and C are each remelted, and the molten metal is atomized by spraying argon gas as a cooling medium.The following two types of rapid solidification are achieved by setting the atomization conditions and sieving the atomized powder. A powder was prepared. (1) Cooling rate: less than 10 ² to 10 ³ ℃/sec Particle size: 32 to 100 mesh (500 to 150 μm) (2) Cooling rate: 10 ³ to 10 ⁵ ℃/sec Particle size: -100 mesh (average particle (diameter: approximately 44 μm) The rapidly solidified powder described above was hot pressed at a temperature of 400° C. and preformed into a billet with a diameter of 60 mm. The billet described above is then heated at a temperature of 450 to 510°C.
Hot extrusion molding was performed at an extrusion ratio of 25 to produce a round bar with a diameter of 12 mm. Table 2 shows the alloys of the present invention produced in this way.
These are the component compositions of Nos. 1 to 4 and Comparative Alloys Nos. 1 to 6, extrusion temperature during hot extrusion, and tensile properties at room temperature. Comparative alloys Nos. 1 to 3 have slow cooling rates that are outside the scope of the present invention, and comparative alloy No. 1 has a component composition that is outside the scope of the present invention. Comparative alloy No. 4 has a composition outside the scope of the present invention. And comparison alloy
In No. 5 and No. 6, the molding temperature by hot extrusion is high and outside the range of the present invention. As is clear from Table 2 above, the invention alloy No.

[Table] Samples 1 to 4 are excellent in both tensile strength and elongation. On the other hand, comparative alloys No. 1 to 3 have slow cooling rates that are outside the range of the present invention, so the desired strength cannot be obtained, and in particular, the composition of comparative alloy No. 1 is also outside the range of the present invention. Therefore, the strength is particularly low. Comparison alloy No.4
Although the cooling rate and molding temperature are within the range of the present invention, the strength is low because the component composition is outside the range of the present invention. Comparative alloys No. 5 and 6 are
Since the molding temperature (extrusion temperature) is high outside the range of the present invention, both tensile strength and elongation are low. Example 2 As shown in Table 3, inventive alloys Nos. 5 to 14 having compositions within the range of the present invention and comparative alloys Nos. 7 to 16 having compositions outside the range of the present invention were melt-produced. did. These alloys were remelted, the molten metal was rapidly cooled and solidified by argon gas atomization by spraying argon gas as a cooling medium, and sieved to prepare a -100 mesh rapidly solidified powder. Its cooling temperature is 10 ³ to 10 ⁵ ℃/sec
It was hot.

【table】

〔Effect of the invention〕

As detailed above, according to the method of the present invention, conventional high-strength aluminum alloys for drawing can be
It is possible to manufacture aluminum alloy members that have room temperature strength comparable to 2000 series alloys and 7000 series alloys, extremely high high temperature strength compared to conventional aluminum alloys, and moderate elongation. Since this process can be carried out using conventional melt-casting materials and hot forming, it can be applied in a wide range of applications and brings about many excellent industrial effects.

Claims (1)

[Claims] 1. An aluminum alloy having a composition consisting of Mn: 4.0 to 12 wt.%, Mo: 0.2 to 4.0 wt.%, and the remainder: aluminum and unavoidable impurities is melted, and then the aluminum alloy is 10 ³ ℃/sec
Rapid solidification is performed at the above cooling rate to prepare a powdery or flaky solidified body, and the solidified body thus obtained is directly used as
or preformed and at least once at 500℃
1. A method for producing a high-strength aluminum alloy member, which comprises hot forming at a temperature of: 2 From the group consisting of Mn: 4.0 to 12 wt.%, Mo: 0.2 to 4.0 wt.%, Fe: 0.1 to 4.0 wt.%, Ni: 0.1 to 4.0 wt.%, Co: 0.1 to 4.0 wt.% An aluminum alloy having a composition of at least one selected element with a total content of 4.0 wt.% or less, the remainder: aluminum and unavoidable impurities is melted, and then the aluminum alloy is heated at a rate of 10 ³ /sec or more. Rapid solidification is performed at a cooling rate to prepare a powdery or flaky solidified body, and the solidified body thus obtained is directly used as is.
or preformed and at least once at 500℃
A method for producing a high-strength aluminum alloy member, which comprises hot forming at a temperature above, thereby producing an aluminum alloy member having a predetermined shape and high strength.